Germany and France say Russia-backed separatists in eastern Ukraine likely shot down a drone being used by the Organization for Security and Cooperation in Europe's (OSCE) monitoring mission, and demand that those responsible âbe held accountable.â

In a joint statement on November 1, Berlin and Paris also noted that in recent weeks, the drone had observed convoys entering Ukrainian territory across a nonofficial border crossing from Russia on "multiple occasions" and spotted a surface-to-air missile system before the loss of communication.

Fighting between Ukrainian government forces and the separatists has killed more than 10,300 people in eastern Ukraine since April 2014. Russia has repeatedly denied financing and equipping the separatist forces despite overwhelming evidence to the contrary, insisting that the fighting wa s a civil, internal conflict.

Germany and France, which have been working with Moscow and Kyiv as part of the so-called Normandy Format to bring an end to the conflict, said the drone operated by the OSCEâs Special Monitoring Mission (SMM) disappeared in the early hours of October 27.

The incident occurred while the long-range drone was following a convoy of trucks near the town of Nyzhnokrynske close to the Russia-Ukraine border, an area controlled by the separatists, the statement said.

It said evidence assembled by the SMM âsuggests Russia and the separatists it backs bear responsibilityâ for the downing of the unmanned aerial vehicle.

The âsevereâ incident âstands in clear violationâ of the SMM mandate as adopted by participating states of the OSCE mission, Germany and France said.

The SMM, a civilian mission assigned to report impartially on the situation in Ukraine, has hundreds of monitors in the countryâs east where the sepa ratists are holding parts of Donetsk and Luhansk regions.

The mission said in March it was reintroducing its long-range drone program more than 18 months after it was halted due to repeated shoot-downs.

Fighting in eastern Ukraine persists despite cease-fire deals reached as part of the September 2014 and February 2015 Minsk accords, and implementation of other measures set out in the deals has been slow.